Propeller



A. BOERNER.

PROPELLER.

APPLICATION FILED OCT. 20. |920.

Patented Auf.

LSSAQO.

l With increasing altitude UNITED STATES Patri-:NTl Ormes.v

ARNO BORNER, F SCHEVIENINGEN, NETHERLANDS.

rRorELLER.

Specitcation of Letters Patent.

Patented Aug. 2, 1921.

Application led October 20, 1920. Serial N o. 418,272.

To all whomt may concern Be it known that I, ARNO BOERNER, hav ing no nationality`,residing at Scheveningen, Netherlands, have invented certain new and useful Improvements in Propellers, of which the following is a specification.

s is well known, the number, of revolutions of an aircraft engine is limited to a definite amount So long asthe propeller is directly connected with the engine shaft. In

the motive power supplied with a certain number ofrevolutios. The resistance depends, however, on the density of the medium in which the propeller operates. the *atmospheric pressure decreases and likewise the density o f the air decreases, sothat the propeller is .no longer able to balancethe generation of motive power. 1n consequence, the number of revolutions is prejudicially increased, to

, power supplied has not increased in avoid which throttling is necessary with loss of` eciency.

So long as the engines were themselves under the influence of fluctuations of at mospheric pressure, while the induction of p gave at greater altitudes rareed mixture an eliiciency less than normal, this drawback was not so serious. Inasmuch, however, as in recent times the practice has come to be to supply the engines with compressed air, thus insuring that the eiliciency of the engine will be maintained constant independently of the elevation of the craft, the capacity of the propeller to consume the proportion and balance is only restored with v an excessive number of revolutions.

' It has already been proposed, for the purpose of maintaining approximately constant the number of revolutions of aircraft engines,

[to construct the driven propeller as an automatic governor'. 1n this construction the propeller blades are radially movable4 outward in relation to the propeller shaft in loosses on the shaft under the influence of centrifugal force and in opposition to the actionof springs in such wise that the springs receive the entire radial pressure of the blades. rllhis construction suffers from the drawback that the springs must be disproportionately heavy. Further, in such prior construction the spring pressure was in radial direction so that the stress of the springs,I

was itself dependent on .the centrifugal force.

lized primarily by `by centrifugal force. I operation, Jthe resistance ofthe propeller Th consumes e accompanying drawing illustrates by way of example one embodiment of the invention; Figure 1 is a longitudinal section partly in elevation and Fig. 2 is a section on the line A-A of Fig. l.

Referring to the drawing, the propeller blades 1 are each secured at the inner end within a sleeve 2 which is slidably fitted in a radial boss 4 rigidly connected .with the propeller shaft 3. A pin 5 extending through the blade and sleeve projects at both ends into helical slots 6 of the boss 4 so that outwardly directed movement of the blade mvolves also an increase of pitch. The

sleeve 2 is formed with. an internal ledge 7 lsupporting one, race ring of a ball bearing of which may be regulated in known maiiner, one end of said spring abutting against a cap 19 and the other against a plate 20 forming a piston. The plate 20 presses against the free end of the lever arm 15 which lfor this purpose is provided` with rollers 21. A rod 22 secured to the plate 20 serves to guide the latter.

The pressure of the spring l8aga1nst the lever 15 tends to hold the pins 10 and thereby the propeller blades in theirinnermost position even when the propeller-'rotates at normal speed. VAs soon, however, as the number of revolutions Lexceeds `a certain limit in flying at a high altitude in conse-4 quence of the diminished resistance of,

through a slot 16 of an axial sleevel? ix- 'edly connected with the shaft 3 and carryl ing the boss 4f. Located within the sleeve 17 is' a helical spring 18, the initial stress increased by with the slot 6.

. site ends' of the levers,

faction nf centrifugal force, shifting the eccentric 12 and compressing the spring l8. the pitch of the blades being simultaneously ln the example illustrated the blade pressure is transmitted by means of eccentrics to the spring 18. lt is evident, however, that any other system of levers may be employed, although the illustrated arrangement has been found excellent for the purpose on account of its compact construction. Further, an airA cushion or buller may be substituted for the spring 18, the stress of which cushion may be regulated during operation.

'laving now particularly described and ascertained the nature of my said invention and in what manner the same is to be performed, l declare that what l claim is f1." A propeller having the blades thereof movable radially under centrifugal force, a spring resisting said movement, and levers intermediate the blades and spring to transmit the outward movement of the blades to the spring in reduced power ratio.

2. A popeller having the blades movable radially under centrifugal force, a spring yacting in line with the propeller shaft, and levers intermediate the ,blades and spring serving to transmit the outward movement of the blades to the spring in reduced power ratio. X

3. A propeller for aircraft having the blades thereof movable radially, a resisting spring, levers coperating at vine end with the spring, eccentrics carried /by the oppoand"means for shifting eccentrics in the' outward movement of. the blades to transmit the, 'lade movement to the spring through said evers.

4l. An aircraft propeller having 'th/e blades thereof movable outwardly under centrifu v the coperation of the pin 5r assenso gal force,

5.. An aircraft propeller having the bladesthereof movable outwardly under centrifugal force, a resisting means for said blade movement including a spring arranged at right angles to said movement and a series of levers intermediate the blades and spring respectively connected said, levers being through eccentrics to the blades. I 'f 6. An aircraft propeller having the blades thereof movable outwardly undercentrifugal' force, a resisting means for said blade movement including a spring right angles to sai'Lmovement and a series of levers intermediate the blades and spring, the blades being turned in theirmovement under centrifugal force to vary4 their pitch.

7. An aircraft propeller having thereof movable outwardly under gal force, a resisting means for said blade the blades:

centrifuarranged at y movement including a rotating member mounted in the blade,'pins leccentric with relation to said member, means connecting the pins of opposed blades, and. spring means to resist the movement of said rotating member. i

8. An aircraft propeller having the blades thereof movable outwardly under centrifugalforce, a'esisting means for said blade movement including av rotating member mounted .in thev blade, pins eccentric with relation to sald member, means connecting the pins of oppsed blades, and spring means to resist the movement of said rotating member, and means whereby the blades change their pitch during under centrifugal force. y ln testimony whereof l alix my si nature.

' p ARN@ BOER ER.

their movement l 

